Molecule structure of 4-Phenylazo-1-naphthylamine (CAS NO.131-22-6) :

IUPAC Name: 4-phenyldiazenylnaphthalen-1-amine 
Molecular Weight: 247.29452 g/mol
Molecular Formula: C₁₆H₁₃N₃
Density: 1.17 g/cm³
Melting Point: 123 °C
Boiling Point: 451.4 °C at 760 mmHg
Flash Point: 226.8 °C
Water Solubility: 1.680 mg/L
Appreance: red-violet light-emitting needle-shaped crystals   
Molar Volume: 210.8 cm³
Polarizability: 30.38*10^-24 cm³
Surface Tension: 47.7 dyne/cm 
Enthalpy of Vaporization: 71.04 kJ/mol
Vapour Pressure: 2.45E-08 mmHg at 25 °C 
Henry's Law Constant: 5.07E-10 atm-m³/mole at 25 °C
Atmospheric OH Rate Constant: 4.90E-11 cm³/molecule-sec at 25 °C
XLogP3-AA: 4.3
H-Bond Donor: 1
H-Bond Acceptor: 3
Rotatable Bond Count: 2
Tautomer Count: 2
Exact Mass: 247.110947
MonoIsotopic Mass: 247.110947
Topological Polar Surface Area: 50.7
Heavy Atom Count: 19
Complexity: 309
Canonical SMILES: C1=CC=C(C=C1)N=NC2=CC=C(C3=CC=CC=C32)N
InChI: InChI=1S/C16H13N3/c17-15-10-11-16(14-9-5-4-8-13(14)15)19-18-12-6-2-1-3-7-12/h1-11H,17H2
InChIKey: IICHURGZQPGTRD-UHFFFAOYSA-N
EINECS: 205-018-4

 4-Phenylazo-1-naphthylamine (CAS NO.131-22-6) is used to be acid-base indicator. pH4.0 (red) to 5.0 (orange)

 4-Phenylazo-1-naphthylamine (CAS NO.131-22-6) is made from Aniline diazonium salt, and then coupling with α-Naphthylamine derived.

Reported in EPA TSCA Inventory.

Mutation data reported. When heated to decomposition it emits toxic vapors of NO_x.
Hazard Codes: Xi
Risk Statements: 36/37/38
R36/37/38: Irritating to eyes, respiratory system and skin
Safety Statements: 26-36
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice
S36: Wear suitable protective clothing
WGK Germany: 3
RTECS: QJ0360000

 4-Phenylazo-1-naphthylamine (CAS NO.131-22-6)  is also called 1-Amino-4-phenylazonaphthalene ; 1-Naphthalenamine, 4-(phenylazo)- ; 1-Naphthylamine, 4-(phenylazo)- ; 4-[(E)-Phenyldiazenyl]-1-naphthalenamine ; 4-Benzeneazo-1-naphthylamine ; 4-Benzene-azo-alpha-naphthylamine ; BNA . 4-Phenylazo-1-naphthylamine (CAS NO.131-22-6) do not dissolve in water, but rendering the red-brown solution soluble in alcohol, ether and benzene. And It slightly soluble in diluted acid solution rendering a red rose solution.